In general, a vehicle seat sliding apparatus includes lower rails to be fixed to a vehicle floor, upper rails to which a set is fixed and which is provided so as to be movable with respect to the lower rails, and a locking mechanism configured to be capable of restricting the relative movement of the upper rails with respect to the lower rails. The position of the seat in the fore-and-aft direction of the vehicle may be adjusted by releasing the restriction by the locking mechanism and bringing the upper rails and the lower rails into an unlocked state in which the relative movement of the upper rails with respect to the lower rails is allowed.
In the related art, there is a seat sliding apparatus including a so-called walk-in feature configured to bring the locking mechanism into an unlocked state upon a forward folding operation of a seatback, and maintain the unlocked state.
For example, the seat sliding apparatus described in JP 2004-122798A (Reference 1) includes an unlocking lever configured to cause the locking mechanism to perform an unlocking operation by being rotated in conjunction with the forward folding operation, and an unlocked-state maintaining lever configured to engage with the unlocking lever and restrict the rotation of the unlocking lever. In other words, by the restriction of the rotation of the unlocking lever at a position where the locking mechanism is caused to perform an unlocking operation, the unlocked state is maintained. In the seat sliding apparatus, a sensor bracket is provided on the lower rails, and at the time of walk-in, the unlocked-state maintaining lever comes into contact with one end of the sensor bracket by the relative movement of the upper rails with respect to the lower rails. With this contact, the engagement between the unlocked-state maintaining lever and the unlocking lever is released, and hence the maintenance of the unlocked state is released.
Here, in this related art, the sensor bracket extends along the longitudinal direction of the lower rails. The unlocked-state maintaining lever is configured to come into abutment at a distal end thereof with an upper surface of the sensor bracket at most seat positions except for a part on the front side of the vehicle by being urged to rotate. Then, at the time of the walk-in, the unlocked-state maintaining lever is moved apart from the upper surface of the sensor bracket at a seat position at the front of the vehicle, and the unlocked-state maintaining lever is rotated and engaged with the unlocking lever, so that the unlocked state is maintained.
In other words, in the general walk-in action, the seat is moved forward of the vehicle from the rear side of the vehicle. Therefore, by forming the sensor bracket so as to extend in the longitudinal direction of the lower rails, and bringing the distal end of the unlocked-state maintaining lever on the upper surface thereof as described above, the unlocked-state maintaining lever is prevented from getting stuck with the sensor bracket in a middle of the state in which the seat is moved forward of the vehicle.
By the rotation of the unlocked-state maintaining lever in association with the movement apart from the sensor bracket, the distal end of the unlocked-state maintaining lever is arranged on the lower side with respect to the upper surface of the sensor bracket. In other words, when the seat is moved rearward of the vehicle again, the distal end of the unlocked-state maintaining lever comes into contact with one end of the sensor bracket. Then, with this contact, the engagement between the unlocked-state maintaining lever and the unlocking lever is released and the maintenance of the unlocked state is released, so that the movement of the seat is restricted at the predetermined position (a fixed point).
However, with the sensor bracket extending in the longitudinal direction of the lower rails as described above, design flexibility of the seat is lowered. Then, in particular, in vehicles having a plurality of rows of seats or vehicles having long lower rails or the like, there is a problem that the length of the sensor bracket may be a significant constraint in design. In this regard, there still remains a room for improvement.
A need thus exists for a vehicle seat sliding apparatus which is not susceptible to the drawback mentioned above.